1. Field of the Invention
The present invention relates generally to a printing apparatus and a printing registration method. More particularly, the invention relates to a technology for enhancing printing registration upon a bidirectional printing performing printing during a forward scan and a reverse scan of a printing head or upon printing employing a plurality of printing heads.
2. Description of the Related Art
Conventionally, printing registration of this kind is generally performed in the following manner.
For example, upon printing registration in a forward scan and a reverse scan upon performing bidirectional or reciprocal printing, a relative printing registration condition for bidirectional scan is varied by adjusting respective printing timing in the forward scan and the reverse scan to perform printing ruled lines on a printing medium by performing the bidirectional scan in respective conditions. Then, a result of printing is observed by a user or the like to select the printing condition where best printing registration is achieved and to set the printing condition concerning printing registration in a printing apparatus, a host computer or the like.
In printing registration between heads when a plurality of printing heads are employed, the ruled lines are printed by respective heads with varying the relative printing registration condition to select the printing registration condition where the best printing registration is attained, by the user or the like, similarly to the above, to set the selected printing registration condition in the printing apparatus, the host computer or the like.
However, in such conventional printing registration method, it is required to select the printing registration condition with observing the result by the user or the like and to perform an operation for setting the printing registration condition to make the operation troublesome. Certain users, for whom such troublesome operation is unfavorable, do not perform printing registration to use a printing apparatus in a condition containing printing position offset or printing registration error in respective scan of bidirectional printing or between heads.
Furthermore, in the conventional method, printing position can be selected only among respective printing registration conditions of the printed patterns. For further printing registration with higher precision, it becomes necessary to perform printing of greater number of patterns with slightly varying the printing and to distinguish delicate difference among the printed patterns by the user, and to select the printing registration condition. In addition to trouble of the user, it takes a long period in printing registration and require large number of patterns on the printing medium.